Democrats are planning to introduce legislation to ban high-capacity ammunition magazines in the wake of the Las Vegas attack that left at least 59 people dead and nearly 500 more injured.

The proposed ban on the transfer, importation, or possession of magazines that hold more than 10 rounds of ammunition follows separate legislation to ban “bump stocks,” the novelty device that Stephen Paddock appears to have used to make semi-automatic rifles mimic the rapid fire of a fully automatic weapon.

Researchers have long described a previous federal ban on high-capacity magazines as the most effective part of the now lapsed 1994 assault weapon ban, since larger magazines make it easier for a shooter to fire more rounds without pausing to reload.

Mark Barden, whose seven-year-old son Daniel was killed in the 2012 mass shooting at Sandy Hook elementary school, said a ban on higher-capacity magazines would save lives.

“When a person perpetrates a mass shooting, like the one that took the life of my sweet little Daniel, the capacity of a magazine can often determine how many bullets are fired before the shooter is stopped. Each time a shooter must pause to reload can provide an opportunity for bystanders or law enforcement to disarm, distract, or escape – each time can save so many lives,” Barden said in a statement.

“Establishing a maximum magazine capacity is simply the kind of commonsense action we can all agree on to help make our families and communities safe.”

Sandy Hook Promise, the violence prevention organization he helped found, has not endorsed a ban on assault weapons, but it has previously endorsed limits on magazine capacity.

Larger magazine sizes, like 15- or 30-round magazines, are common among American recreational shooters, and even larger 100-round magazines are available for legal sale.

While larger capacity magazines are most closely associated with the death and injury toll in mass shootings, a 2016 investigation from the Baltimore Sun found they play an increasingly prominent role in gang-related violence in cities like Baltimore, where the city’s medical examiner found that the number of cadavers with 10 or more bullets had more than doubled in the past decade. Gun violence in several cities nationwide had become more lethal in recent years, the investigation found, with victims more likely to die of their wounds despite advances in emergency medical care.

Gun rights advocates say the pause to reload when changing magazines is very brief and unlikely to have a significant impact on casualties, and that arbitrarily restricting magazine size to 10 rounds would be costly and inconvenient.

These advocates say it is not hard to make larger capacity magazines by hand, even if they’re not available for legal purchase. Chris Koper, the researcher who evaluated the 1994 assault weapon ban, estimated that renewed limits on the size of ammunition magazines might contribute, in the long-term, to a 1% reduction in shootings each year. This was only a “reasonable ballpark estimate,” he cautioned.

A similar attempt to ban high-capacity magazines failed in the US Senate in 2013, months after the Sandy Hook shooting, with 46 senators approving the measure and 54 voting against it.

The new high-capacity magazine ban legislation will be introduced in the House by Elizabeth Esty, a Democratic congresswoman who represents Newtown, Connecticut, the site of the 2012 Sandy Hook shooting, and several Democratic House members from Nevada, where the Las Vegas shooting took place.

Passing gun control regulation remains an uphill fight in a Republican-controlled Congress.

Some Republican legislators facing tough re-election campaigns have endorsed a legal ban on bump stocks, a little-known “range toy” that appears to have been used in Las Vegas, the deadliest mass shooting in recent American history.

But other Republicans, including House speaker Paul Ryan, have said that they believe the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) will be able to regulate “bump stocks” appropriately without a new law.

The ATF previously ruled that bump stocks did not fall under the regulation of federal firearms laws, including the law that strictly regulates fully automatic weapons.